The present invention relates to motor vehicles and in particular to a wastegate control system and a method for controlling a wastegate.
Methods of controlling a wastegate have been previously proposed. Severinksy (U.S. patent number 2006/0237247) is directed at a hybrid vehicle, including an internal combustion engine. Severinsky teaches a wastegate that is implemented as a spring-loaded relief valve to limit the boost provided. Furthermore, the wastegate of the Severinsky design may take intermediate positions between fully-open and closed positions. Severinksky discloses the possibility of adjusting the wastegate to respond to an atmospheric-pressure signal provided by a suitable sensor to ensure that adequate boost is provided at higher altitudes to ensure vehicle performance.
Weinzierl (U.S. Pat. No. 7,104,352) is directed at an intercooler system and a method for a snowmobile with a supercharged engine. Weinzierl discloses a wastegate coupled to a turbine to allow for exhaust bypass of the turbine if the pressure of the charge air is too high. Furthermore, both the wastegate and the injector valve are controlled by an engine control unit, which makes use of inputs from an intercooler liquid level sensor, a charge air temperature sensor, and a knock sensor, in addition to other conventional inputs to the engine control unit.
Hartman (U.S. Pat. No. 6,779,344) is directed at a control system and method for a turbocharged throttled engine. In the Hartman design, engine exhaust flows from the engine to a turbocharger turbine and a wastegate valve to the exhaust. The wastegate is controlled according to an algorithm. During one step of the algorithm, the desired manifold pressure is retrieved according to an earlier step. A desired offset may be added to the manifold pressure during another step, giving a desired boost pressure value. The maximum boost is computed during another step. Hartman teaches that the maximum allowable pressure boost is computed in a known manner using the air flow rate and the known stored compressor characteristics. Following this, during the next step, the maximum boost is compared with the desired boost. If the desired boost is greater than the maximum boost, the desired boost is reset to equal the maximum boost. Otherwise, the desired boost level is kept the same. During another step, the wastegate is controlled according to the desired boost.
Wong (U.S. Pat. No. 6,694,242) is directed at a dual fuel engine having multiple dedicated controllers connected by a broadband communications link. The Wong design teaches a dual fuel engine that can operate in a dual fuel mode or in a diesel only mode. Both dual fuel controller and the diesel controller receive various types of inputs. In the Wong design, the dual fuel controller receives signals from a gas pressure sensor and a gas temperature sensor, and possibly other sensors. The diesel controller receives signals from a timing/speed sensor (also connected directly to dual fuel controller) and from a crankshaft speed/timing sensor. The diesel controller may further receive signals from a boost pressure sensor, an intake manifold air temperature sensor, an atmospheric air pressure sensor, an oil pressure sensor, a diesel fuel temperature sensor, an ambient temperature sensor as well as possibly other sensors.
Based on data received and/or calculated from the various sensors, the dual fuel controller transmits signals to the gas injectors, the gas shut-off valve, and the turbo wastegate control valve. Also, the diesel controller operates according to signals received from the various sensors, as well as signals received from the dual fuel controller.
Zimmer (U.S. Pat. No. 6,134,888) is directed at a turbocharger control management system. Zimmer teaches the use of an electronic turbocharger control system for an internal combustion engine that is provided to control at least one turbocharger by controlling a bypass valve and a wastegate in response to the engine speed, engine load, ambient temperature and the operating environment's barometric pressure. In particular, a turbocharger control module has a plurality of engine characteristic signal inputs, including an intake manifold pressure signal, an engine speed signal and an ambient temperature signal. These signals are determined according to a manifold pressure monitor, an engine speed monitor and an ambient temperature monitor, respectively. Based on characteristic values for these signals, a predetermined setting for the wastegate is selected from a group of predetermined settings.
Houtz (U.S. Pat. No. 5,974,801) is directed at a turbocharger control system. Houtz teaches a wastegate valve connected between the exhaust manifold and the turbine section that is movable between an open position at which fluid flow exhausted by the engine is free to bypass the turbine and a closed position at which fluid flow exhausted by the engine is restricted from bypassing the turbine. Several sensors are included in the Houtz design that are used to determine a control signal for the wastegate valve. The sensors include: a first means that senses the speed of crankshaft, used to determine the engine speed; a second means to sense the boost pressure of the engine; a third means that senses a rack position of the engine; and a fourth means that senses the barometric pressure of the engine environment.
Emmenthal (U.S. Pat. No. 4,322,948) is directed at an internal combustion engine comprising an exhaust driven turbocharger for generating maximum boost pressure in the intake manifold. The Emmenthal design includes a knock sensor that detects engine detonation and, in response, causes actuation of a valve for temporarily reducing the boost pressure such that knocking subsides.
While the prior art teaches the use of several sensors that may be associated with a wastegate controller, there are several shortcomings. The prior art lacks any use of a throttle angle sensor in association with a wastegate controller. Furthermore, the prior art lacks any reference to an intake charge humidity sensor that may be associated with a wastegate controller. There is a need in the art for a wastegate control system that makes use of a throttle angle sensor and an intake charge humidity sensor.